DEWMA Control Chart for the Coefficient of Variation

Abstract:

When the production run is short and process parameters change frequently, it is difficult to monitor the process using traditional control charts. In such a case, the coefficient of variation (CV) is very useful for monitoring the process variability. The CV control chart, however, is not sensitive at small shift in the magnitude of CV. The CV-EWMA (exponentially weighted moving average) control chart which was developed recently is effective in detecting a small shifts of CV. In this paper, we propose the CV-DEWMA control chart, combining the DEWMA (double exponentially weighted moving average) technique. We show that CV-DEWMA control chart perform better than CV-EWMA control chart in detecting small shifts when sample size n is larger than 5.

• Periodical: Advanced Materials Research (Volumes 201-203)
• Pages: 1682-1688
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.201-203.1682
• Online since: February 2011
• Authors: Eui Pyo Hong, Hae Woon Kang, Chang Wook Kang
• Keywords: Coefficient of Variation, Control Chart, DEWMA, EWMA

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